<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    * {
        margin: 0;
        padding: 0;
    }
    
    li {
        list-style-type: none;
    }
    
    .box {
        width: 250px;
        margin: 100px auto;
    }
    
    .box li {
        float: left;
        width: 24px;
        height: 24px;
        background-color: pink;
        margin: 15px;
        background: url(images/sprite.png) no-repeat;
    }
</style>
</head>

<body>
    <div class="box">
        <ul>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
            <li></li>
        </ul>
    </div>
    <script>
        //1,获取元素
        var lis = document.querySelectorAll('li');
        for (var i = 0; i < lis.length; i++) {
            //让索引号乘以44  就是每个li  的背景y坐标
            var index = i * 44;
            lis[i].style.backgroundPosition = '0 -' + index + 'px';
        }
    </script>
</body>

</html>